It is often desirable to analyze properties of an object that has been cooled to very low temperatures, such as cryogenic temperatures, for example temperatures close to that of liquid nitrogen. When analyzing a gem, for example, it is often desirable to perform a spectral analysis of the gem at cryogenic temperatures to obtain information about the composition of the gem. Performing a spectral analysis on a gem cooled to such temperatures is particularly useful, for example, in determining the color origin of diamonds which may have been subjected to various treatments such as irradiation, as in a nuclear reactor or by an electron beam, or annealing, and for identifying diamonds treated under high-pressure and high-temperature (HPHT).
Currently available cooling apparatuses exhibit a number of disadvantages. For example, some currently available cooling apparatuses require a test sample to be cooled for approximately 20-30 minutes before a spectral analysis could be performed. Such a prolonged cooling period severely limits production capacity when a large number of gems need to be analyzed. Other apparatus employ direct immersion of the gemstone in the cooling medium which may result in undesirable interaction between the cooling medium and spectral information of interest. Still other cooling arrangements have employed a cylindrical copper block of approximately 2 inches in diameter, 1.8 inches in height, and having a 0.16 inch diameter bore along its axis, and which has been cooled to a desired temperature and removed from the cooling environment prior to placement of the object to be cooled in the 0.16 inch diameter bore.
Another disadvantage of some of the currently available cooling apparatuses is that they are bulky and complex. Some of these apparatuses, for example, require the test sample to be placed within a shell that is submerged in liquid nitrogen. Because of condensation that may occur within the shell, however, such apparatuses require a mechanism to infuse moisture-free gas into the enclosed internal chamber occupied by the test sample. As such, in addition to the extra time required to infuse gas into the shell, these apparatuses add additional costs to the analysis task, and because of their complexity are more prone to mechanical failure.
Accordingly, there is a need for a method and apparatus for rapidly cooling gems in an efficient and cost effective manner. More specifically, there is a need for a method and apparatus for cooling gems which does not require a closed environment, or infusion of moisture-free gas, and which allows for a rapid cool down and analysis of a large number of gems.